Sorting apparatus



March 19, 1940. H. w. CADMAN SORTIING APPARATUS Filed Sept. 16, 1937 5Sheets-Sheet 1 March 19, 1940. H, w, CADMAN 2,194,381

SORTING APPARATUS Filed Sept. 16, 1937 5 Sheets-Sheet 2 5 Hi-fin": Wflflg March 19, 1940. I H, w, CADMAN 2,194,381

. SORTING APPARATUS Filed Sept. 16, 1937 5 Sheets-Sheet 3 v jnrevf/lMarch 19, 1940. H. w. CADMAN SORTING APPARATUS Filed Sept. 16, 1957 5Sheets-Sheet 4 March 19, 1940. H. w. CADMAN ,194,381

SORTING APPARATUS Filed Sept. 16, 1937 5 Sheets-Sheet 5 J55 J55 7 JJQJY/jzi ww W Patented Mar; 19, 1940 I I ,sonrmonrrAaArns liuberjt williamGadman, Eltham, London, Eng I land, assignorto sovex Limited, Erith,England, '3 qa cornpany of' Great Britain 7 Application*SeptenibrLlB,1937, Serial No. 164,224 I h H In Great. Britain January 26, 1937 16Claims. (01. 214-11) This invention concerns improvements relav ing tosorting and distributing apparatus for parcels, particularly for the useof postal authorities, of the kind in which an endless distributing -5conveyor passes a sorting station and a series of receiving stations anda sorting oiiicial' at the sorting stationm'anually sets a selectivecontrol means wherebyparcelstransported'by' the conveyor are caused tobe 'dischargedtherefrom at the proper receiving stations. object of theinvention is to provide a simple. apparatus which takes proper accountof the diiiiculties to be overcome if parcels" areto be reliably andsafely sorted and distributed. These difficulties 6- are not the same asthose which'are encountered in the sorting ofletters-or cards andaarise"especially from the necessity forcaring for avery wide range of sizesand kinds of parcels, including bulky parcels and also fragile parcels.0 'According-tothe' invention, parcel-sorting and distributing apparatuscomprisesa continuously operating distributing conveyor havi'ng'a seriesof compartments and, arranged topass a sorting station and a series ofreceiving-stations, com- 25 pertinent-discharging means at eachreceiving station, and control means including manually set selectionmeans located at the, sorting station and discharge-effecting means eachallotted to 'the discharging means at a respectiverece'iving '30-station, each discharge-effecting means- -being directly associated'withthe selection means for be- 7 ing selectively rendered active uponactuation ua'ereof'and associated with'the conveyorfor' being advancedin step with theoonipartrnent's .to-

wardsa' discharge-enacting condition in such fashion that thecompartment passing the sorting station at the time when the selection;means i is actuated is caused to be discharged as it passes theaforesaid receiving station,

40;, In contradistinction to arrangements inserting.

apparatus proposed heretofore,- the aforesaid dis- I charge-effectingmeans is rendered active, that is, prepared for effecting discharge,directly by. the.

selection means, that is, without. the interme' 45 diary of registerdevices carried by orotherwise permanently allotted to; respective;compartments of the conveyolx, v I

' Also in accordance with the present invention,

parcel-sorting and distributing;apparatus comto, prises acontinuouslyoperating distributing conveyor having a series of compartments andarranged to pass a sorting stationanda series of receiving stations,manually actuated, selection urea-us at. the sorting station,v timingmeans opermated, by or with the conveyor, compartment quired number ofsorting selections.

charging means at the sorting station adapted for "being caused tooperate by actuation of. the

selection means and under control 'ofth'e timing means so that eachparcel is charged into a" definite compartment in position'for receivingit, .5 discharging means at each receiving station; dis--charge-effecting means '-eaol1 adapted for being selectively set inaction by actuation of the r'selectio'n means and under control of thetiming means and each allotted to a respective rec'eiv- 10- ing stationand operatively related; to the dis,- charging means at thesaid stationfor causing discharge there of that compartment which is. in positionfor receivingthe parcel when the charging means is caused to'ope'rate.

- A preferred embodiment of the invention in-. tended for the sorting.of postal'parcels will now he described by Way of example and with refs,

erence to the accompanying drawings, in which: 7 Fig. 1 is adiagrammatic side elevation of'a'n installation of apparatus inaccord'ance with the invention, I, p I

Fig, 2 a similar plan View of the conveyors; V Fig. 3 aside elevation toa larger scale of'paiit:

of a distributing conveyor-and the associated chute and trap-door gear,Fig. .4 a plan 'view to a larger scale ofhpa'rts of several distributingconveyors, v Fig. 5 a side' elevatio'n partly in section on V-V..

in Fig.- 6, to yet a larger scale of electro-mechan 3o,

, ical discharge-control means,

. Fig. 6 a view at right angles to Fig. 5, Fig, 7 a side view of a boxshowing the latchj ing J means, I 1

Fig. 8 a vertical section of the far end of a' distributing conveyor,showing the" relatchin'g' means, and j ,Y i

:Flg. 9 a circuit diagram; -.r Referrin primarily to Figs. 1' and 2, thedisk tributing conveyors comprise a train of boxes i of shallow hoppershape carried between'endlfess roller-chains 2 which run oversprocket-wheels.

'3, r A number of such conveyors (four in Fig. 2) corresponding to. thenumber of sorting stations 4 extend parallel to each other in ahorizontal plane. The receiving conveyors comprise ar-a1 lel endlessconveyor bands 5 5 5 -extend-fi ing, with partitions 6 betweenthem, atright time jg'le's to'the distributing conveyors and-located;

below the upper, effective, flights of ,the 1atter.-50'-,

There is a number, of these receiving conveyors (as illustrated, twelve)-,corresponding to' the re- Y The range of sorting stations 4 ,extendsabove adjacent ends ofthe; distributing conveyors and will generally beaccommodated upon the next floor of the building. Preferably thestations each comprise a sorting table containing an opening normallyvated platform Ill.

At each station '4, there is a. row of press-button switches H H H M(Fig. 4), one" As hereinafter, de-

" chanical and the secondelectrical.

each switch except H controls electro-mechanclosed by trap-doors 1 frombelow which an in clined chute 8 leads down to a point above the end ofthe associated distributing conveyor. Each station is suitably suppliedwith parcels to be sorted, for example by a'glissade 9, from an eleforevery receiving conveyor. scribed, the switches serve twofunctions.Firstly, each switch, when depressed, allows the trapdoors I to openwhen a box of the distributing conveyor is approaching the correctpositiornor is correctly positioned, to receivea parcel byway of thechute 8. For this purpose',.-.the control gear for the trap-doors ismade to comprisetwo elements, a first element which operates in timedrelation with the associated distributing conveyor. and which wouldpermit release, of the trap-doors each time a box l approaches the corvrect position and a second element which permits one such release onlywhen a switch has been depressed. Conveniently the first element is me-Secondly,

ical means over one particular receiving conveyor 5 5 whereby the box. Iinto which the parcel has been deposited is caused to discharge the sameupon arrivingabove that conveyor.

v A preferred formof control for the trap-doors I is illustrated in Fig;.32 Forthe first element of this control, rollers E2 on the axles li 'lcarry.-

ing the1'rollers2 and connecting the links 2 of one of the chains 2 areutilized as operating members. These rollers 12 co-act with a shapedlever 1.3 which is pivoted at Hi and is connected by an arm l5 and linkIt to a bell-crank lever I1 pivoted at it. An abutment l9 pivoted onthe.

lever 11 is held upwardlyby a strong compression-spring 20 and iscapable, in the position illustrated by chain lines, of afiordingsupport to a. lever 2| freely pivoted at iii-and connected by a link 22to trap-door release linkage 23. The

lever, 2| is normally supported in the, position illustrated by a catchzi which is connected to the plunger of a normally unexcited solenoid25...;This1ast arrangement constitutes the sec-g ond element of thecontrol; g

It will be seen that'as long as the solenoid 25 remains unexcited, thelinkage 25-523 will be held in the position illustrated and the doorsclosedirrespective of the condition of the linkage I-3.-l1. If, however,the solenoid operates to re lease the catch 24, the doors 7 will be heldclosed only while the linkage iii-ll" is in the position shown by chainlines in Fig. 3, that'is while the lever 13 is engaged on one of itsflats I3 43 by'a. roller l2. As soon as a roller. enters therecess l3,however, the linkage 2I-23 will be completely released andthetrap-doors will fall 1 open. The recess I3 is sodesigned that thishappens when a bowl is approaching the correct position for receivingaparcel. As the'roller sub sequentlyruns on to the fiat R3 the doors '1will. be raised through the linkage l3-H-,'the

.abutment l9 and linkage 2l--23 and willthenbe ,locked closed by thecatch 2d controlled by the solenoid, 25, now unexcited.- A

-Inthe arrangement illustrated in Fig. 3,'c1o-' sure means for the lowerend of the chute B and control means therefor are also provided: A loop.;:of beltingilfi is anchored at one end 2'1 and is;

rollers l 2.

the chute and catches without shockparcels fall,-

ing from the trap' doors 1, while the upper part of the said mouth isclosed by a stop-flap 3i hav-Y ing an arm 32 connected to'a link 33.This link has a" pin and slot connection 34 with the lever ,i

29an'd a pivotalconnection with a shaped lever 35 which is pivoted at 35and is actuated by the Each time a box 1 reaches the correct 7positionbelow the chute, the lever 35 moves from- I I the full-line thechain-line position in Fig; 3 and thereby causes the belting 26 to belowered and the stop 3! -'raiseds'o'that any parcel in the loop isconnected at the other end to a cross-bar 28. I supported by a lever '29pivoted at 3! This loop normally closes the lower part of the mouth'of.

deposited safely and correctly in the box 'i. Pare;

- ticularly with a'more gently sloping chute, this ad- Y ditionalclosure means may be dispensed with, but

the controlmea'nsfor the trap-doors I must then be carefully timed sothat a parcel therefrom reaches: the box tion. t;

A preferred form of electro-mechanical means over 'each receivingconveyor, 5 -5 is shown-in lqwhen it is in the correct posi- Figs. 5 and6: A round disc 31 containing a ring of studs 38 slidable-in a.direction parallel to the axis of therdisc-is connected to a ratchetwheel: 33 engaged by a spring loaded pawl 40 whichis. carried by'anoscillatory lever ll. This lever is mounted freely on a stub 42projecting from the wheel 39 and is connected by a, link 43ttoajseesawlever .434 having-one end 45 elevated for en.- gagementby a partconnected to each passing box as illustrated, a'roller l2.v ment resultsin the'lever M being rocked clockwise, raising its bevelled end 45 intoposition for engagement bly the next roller 12 by which the lever isreturned toitsf initial position before being rocked again. Themechanism is support ed from the frame-rail 66, onwhich the rollersZlrun, by a bracket 46%..

The lever is thus rocked Such engagee and actuates the; pawl 48 once:for .each box 1 that passes. The arrangement is made. such that thedisc lllis thereby advanced ,byythe pitch-distance between two studs 38each timea box passes. The-studs,

each controlled by aspring. detent 38 normally occupy an inoperativeposition in which: they an s t 1 project upon one side of the disc, theright hand side inFiglfi'; Mounted on the other side of the I disc onepivot His a spring-loaded trip-lever 49- whichnormally occupies; an-inoperative'.po--

sition, illustrated in full lines inFig. 61- in which 56 on its edge.engag'eable byxtl'ie side of any stud it overlaps the disc. "This leverhas a cam-face '1 38 projected from the adjacent side of the discfzinafter described, on a passing box for causing the latter to dischargeits contents. The proj'ec tionof ias'tud- 35 to the operative positionis e'f-.

fected through a rocking lever. ,53' by theat-- traction of the co're5'4 o'f'a solenoid SEQ In Fig-I ure-5', the uppermost stud-has justbee-n projected and the 'core'fiihas returned-"to its normal po-psition. In themechanis m over 1 each receivingconveyor 5 5 the angularinterval 56(-Fig. 6)" between the'point atwhich the lever 53 can 'op-"erateto-project a stud 38 and the/point atwhich that smagcan actuate thetrip-lever i9 is equal 2,194,381 to the angular pitch of 'the studsmultiplied by v the number of boxes 1 in the interval between the chute8 and the receiving conveyor in question. Consequently, a-studprojecitedat the time whena parcel is deposited in a box engages the edge-cam 59of the trip-lever to cause opening of that box just as it reaches therequired con'veyon The stud, after riding over the same cam it, runs onto the rear face cam at 5| and is returned to its initial position.

The bottom of each box 1. consists of two hinged fiapsfi t, 65 (Fig.7),"the flap 64 being longer than'the flap 55 and having-a lip S4engaged under the edge of the latter; The flaps are normally held closedby hook-members $5 which are mounted at the ends of a shaft a! carriedon the flap M and-are engaged over studs (58 on the fixed'sideewalls 690f the box. An extension of one hook-member 6B beyond the shaft 61carries a pin H3 located for engagement by the finger 52 of anyprojected lever 49' (Fig. 6). The hook-membersfit are normallymaintainedyin engagement'with the studs ill? by a spring I! (Fig. 6)acting on the shaft Bl. When encountered by a finger 52, however, thehook members are unlatchcd from the said studs 58 and the flaps 54, 65fall down todischarge the contents of the box upon the respectivereceiving conveyors -5 5 Over the last receiving conveyor 5 a stop It,in effect a permanently projected. finger 52, is providedfli'o'rtripping all of the box-latches to ensure that. any parcels remaining inthe boxes I, whether by error or V otherwise, are deposited on thatconveyor. The

hanging flaps-of the boxes are closed partlyby gravity and partly byramps '53 (Fig. 8) as each box passes around the remote sprocket wheel3. Each longer flap G l encounters the ramp l3 and is :swung and held upas shown in Fig. 8. Each shorterflap clears the ramp l3 and inits.

hanging condition comes to lie inside the lip @54 on the flap 64 .as thebox passes downwardly around the sprocket wheel 3. As the box becomesinverted, the liapltrfalls under gravity upon the flap 55 and thehookr-members 65 be come relatchedautomatically with the studs 68.

An appropriate circuit arrangement is illustrated in Fig. 9: Theswitches Il -l E are connected in series with respective solenoids 55--55 and are'arranged upon depression to make con ,nection between thesaid solenoids and a common negative bus-bar 56. A common lead 5'! tothe solenoids is connected through the winding 58 of a relay and thecontacts of a master The contacts 60 of this relay are connected inseries with the solenoid 25 on the one hand and with the winding 58 andswitch 58 on the other. It will be seenthat the relay winding 58, thesolenoid 25 and a preselected one of the solenoids ES -55 are notexcited immediately upon depression of one of the selectedswitches I 1-4 E the master switch 59 must first close. This switch is closedautomatically and periodically for a short interval of time as each boxl approaches the mouth of the chute and ensures that the solenoid 25andselected solenoid 55 55 are synchronously excited in proper timed.relation to the movement. of the'boxes l. The

timing is preferably'also such that the discs 3:?

are at rest when the master switch 59 is closed,

This switch may be located as shown in Fig. 3 and actuated by therollers l2.

The switch I I is connected to the relay -winding 58 through aresistancefil equivalent to-the resistance of a' winding 55 -55Depression of the switch H is thus followed by operation of the relayand excitation of the solenoid 25 only.

Whenever one of the switches il -4 {12 is depressed, it is maintained inthe depressed condition automatically until the trap-doors l op erate.For this purpose the switches may be of the kind which, upon depression,is automatically engaged by a catch and is released only when the catchis withdrawn. As shown, an electro-1nag' net 62 for withdrawing thecatch to release the switches ilk-l I is connected in series withv aswitch 53 which is arranged to be closed momentarily by the link 2?.(Fig. 3)-' as the trap-doors "I operate.

The manner of operation o1 the apparatus as a whole will be readilyunderstood: During sorting, the distributing and receiving conveyors aredriven continuously. A sorter, standing at one" may be commenced atonce, that is without wait-v ing for the actual discharge of the'parcelat the receiving conveyor. A convenient sorting speed 7 of about 20parcels per minute may be maintained in this fashion. v

In the installation illustrated, the four dis tributing conveyors arearranged in pairs (Figs. 2 and 4) with common driving gear extending upbetween the pairs. Each pair of conveyors is supported between twochains 2 and the control means for the trap-doors l and for thedischarge of the boxes l is disposedon the outer sides of the conveyorstor co-action with respectively adjacent chains.

I claim: i 1. Apparatus of the kind set forth, comprising fasortingstation, a series of receiving stations, an endless conveyorcomposed of a chain of com partinents and moving continuously past thesorting station and the: receiving stations in sucsession, chargingmeans at the sorting station, timing means operated. by the conveyor andarranged to control the charging means sothat an article is charged intoa definitecompartment in position for receiving the same, compartmeno.

discharging means at the receiving stations, de layed-action devicesoperated by the conveyor and arranged each'for setting a respectivedischarging means, and selective control meansopveratively associated.with the timing means and the delayed-action setting devices whereby anysetting device can be selected by the control means for being directlyset in action by the timing means at the time of charging, the delayedaction. of each setting device being such that the respectivedischarging means is set to discharge'the article after the time-periodrequired by the charged compartment to move from the sorting station tothe respective receiving station." i

2. Apparatus of the kind set forth, comprising a sorting station, aseries of receiving stations, an endless conveyor composed of a chain ofcompartments and moving continuously past the sorting station and thereceiving stations in :suc-

cession, charging means including a trapdoor at the sorting station,timing means including a master switch closed periodically by theconveyor, an electro-magnet excitable by the said switch and a catchnormally operative upon the charging door to maintain the same closedbut releasable upon excitation of the electro-magnet by the switch toopen the door in timed relationship with the conveyor movement,compartmentdischarging means at the receiving-stations, delayed-actiondevices at the receiving stations including a rotatable member with aring of projectable pins and a ratchet device for driving the saidmember from the conveyor and in timed relationship therewith, therotatable member being arranged so that a projected pin in the course ofthe rotation of the said member will encounter and cause operation ofthe compartment-discharging means at the same station, electro-magneticmeans arranged adjacent to each rotatable member for projecting a pintherefrom, v selective switches at the sorting station each adapted forpreparing exciting circuits through the master switch for a selectedelectro-magnetic means and .the electro-magnet, the angular intervalmeasured on the rotatable member between the elec-v tro-magnetic meansand the compartment-discharging means at a series of charging means ateach receiving station being proportional to the numper of compartmentsseparating that station from the sorting station.

3. In combination with sorting apparatus comprising a conveyor,conveyor-charging means adjacent to a sorting point, anconveyor-disreceiving points; control apparatus comprising anelectro-magnetic release device operatively connected to the chargingmeans, delayed action operating devices respectively engageable witheach of the discharging means and arranged to be driven by the conveyor,electro-magnetic means respectively adapted for setting theoperatingdevices for engagement with the discharging means after the delay inaction of the said devices, manually operated selective switch means forpreparing circuits to the electro-magnetic release device andto aselected 'electro-magnetic setting means,

and a master switch arranged for being closed in timed relation with themovement of the con- I veyor and for completing the said circuits.

4. In parcel-sorting apparatus, in combination with a conveyorcomprising a chain of compartments moving past a charging point and aseries of discharging points, manually operated selective control meansat the charging point and discharging means for each discharging pointincluding a compartment-discharging member, a counting device driven bythe conveyor and adapted for actuating the said member after counting anumber of compartments equal to the number thereof between therespective discharging point and the charging point and means directlyconnected to the selective control means for setting the said countingdevice in operation.

5. In parcel-sorting apparatus, in combination with a compartmentalendless conveyor moving continuously past a charging point and a seriesof discharging devices, control apparatus comprising, for' eachdischarging device, a compartmerit-counting element, means for renderingthe said element operative for actuating the discharging device wherebythe latter is actuated after the said element has been renderedoperative and has counted the number of compartments separating therespective discharging de- I vice from the charging point, and selectionmeans near the'charging point directly connected to the I means forrendering the counting elements operative whereby any selected elementcan be so rendered operative.

6. Control apparatus according to claim 5, wherein the counting elementcomprises a rotatable member, means operatedby the conveyor compartmentsfor rotating the said member in steps, aring of normally retracted butproject able studsslidably mounted in thesaid rotatable member andengageable, when projected, with the discharging device and the'meansforren-f dering the counting element operative comprises.

an electro-magnetic device positioned adjacently to the ring of studsand adapted for projecting that stud which is opposite toit when it isex-v cited, the angular intervalon each. rotatable member between theoperative positions of the electro-magnetic device and the dischargingdevice being proportional to' the distance from the charging point ofthe respective discharging device. 1

7. In combination with'a sectional endless conveyor moving continuouslypast a charging device and a series of discharging devices, control.apparatus comprising first control meansqior.

rendering the charging device operative, second control means forrendering the discharging devices operative, selective manual devicesadapted for preparing the. first control-means and one second controlmeans for rendering the charging device and onefrequired dischargingdevice operative, and 'anautomatic device driven from the sectionalconveyor and adapted for 35. causing the prepared first and secondcontrol means to render the said charging and discharging devicesoperative in syrlchronism with each other and in fixed time-relationwith the 1 movement of the conveyor-sections past the said devices. g kl 8. Control apparatus according to claim 7,

wherein the control means is electrically actuated and the manual andautomatic devices respectively comprise selective switches and anautomatic switch arranged in the vicinity of the con-' veyor so as to beclosed and opened by the conveyor sections 'as they pass. i

9. Control apparatus for controlling ajcombi: nation of a sectionalendless conveyonwhich moves continuously past a charging device, and

past a series of discharging devices, comprising,

firstly, means for controlling operation of the I I charging device,secondly, a manually actuated means for preparing the control means forcalls.-

ing operation of the charging device and consist ing of an electricalswitch, and electro-magnetic device excited under the control of thesaid 1 switch, and a locking means connected to the electro-magneticdevice and acting upon the control means, and thirdly an automaticdevice driven from the sectional conveyor and adapted for actuating theprepared control means to cause i operation of the charging device intimed rela tion with the movement of theconveyor sections past thecharging point, the said device consisting of a further locking meansacting upon the control means and an operative mechanical connectionbetween the sectional conveyor and the:

latter locking means. v

10. Parcel-sorting and distributing apparatus,

comprising a sorting station, a continuously oper-- ating distributingconveyor having a series of;

compartments and arranged to pass the sorting station, a series, ofreceiving stations along said" distributing conveyor, selectivelycontrolled compartment-discharging means at each receiving station,control means including manually actuated selection means correspondingto each receiving station located at the sorting station,

and operating means for the 'compartment-discharging means at eachreceiving station, said operating means comprising elements eachcorresponding to one of the compartments of the distributing conveyor,means for moving said elements in, timed relation with the conveyor tobring said elements into the, proximity of the compartment-dischargingmeans,- and means controlled by said manual selecting means for movingsaid elements into operating position to operate thecompartment-discharging means to discharge its corresponding compartmentwhen it is in position to discharge at the proper" receiving station.

11. Parcel-sorting and distributing apparatus, comprising a sortingstation, a continuously operating distributing conveyor having a seriesof compartments and arranged to pass the sorting station, a series ofreceiving stations arranged along the distributing conveyor, manuallyactuated selection means at the sorting station, timing means operatedin timed relation to the conveyor, charging means at the sortingstation,

, control means for said charging means responsive to the selectionmeans and the timing means for charging each parcel into a definitecompartmerit when'said compartment is in position for receiving it,discharging means at each receiving station, operating means for each ofsaid discharge means at each receiving station, each.

controlled and selectively set inaction by actuation of thecorresponding manual selection means and under control of the timingmeans, each of said operating means corresponding to a respectivecompartment of theconveyor and operatively related to the dischargingmeans at itsstation for causing discharge thereof thatcompartment whichis in position for receiving the parcel when the charging means iscaused to operate and the station selection means has been actuated. I

12. Apparatus according to claim 11, wherein the selection means comprises manually operated electric switches and the timing means includesa switch arrangedto be closed periodically by the conveyor forcompleting a circuit, se-

1 such release each time a compartment reaches the charging point.

14. Apparatus according to claim 11, wherein the charging means includesa chute, a'loop of flexible material which normally closes the chute atitsvlower end for catching falling parcels with little shock, means forlowering the said loop to deposit the parcel gently in the compartment,and control means for the saidlooplowering means operated periodicallyby the conveyor each time a compartment reaches the charging point underthe chute.

15. Apparatus according to claim 10, wherein each compartment of thedistributing conveyor comprises a bottom divided transversely into two.flaps and a self-engaging latch which normally holds the said flapsclosed and is disengageable by the discharging means for allowing theflaps to fall.

' 16 Apparatusaccording to claim 10, and cam means at the returningpoint of the distributing conveyor and, for each compartment of thelatter, a bottom divided transversely into two flaps and aself-engaging-latch which normally holds the said flaps closed and isengageable by the discharging means for releasing the said flaps toallow them to fall open, the trailing flap normally engaging inside theleading flap and being shorter than thelatterso that, in its fallenposition, it clears the cam-means whereas the leading fiap, inits fallenposition, is engageable by the cam-means for rocking the said leadingflap up outside the freely hanging trailing flap,

whereby the said flaps become re-engaged and secured by the latch. r

' v HUBERT WILLIAM CADMAN.

